The straight handstand.
Is this the ideal form? Is this the handstand shape that everyone should aspire to achieve? Perhaps...

It's certainly a good standard to uphold. The straight handstand is efficient from a mechanical standpoint, as it stacks all the joints on top of one another. You can't deny the aesthetic value either; the tall straight line looks good. This form also works well with regards to execution of skills like press handstands, one arm handstand, and many dynamic moves.

What about a counter-argument? First off, creating this shape in your body is not intuitive, so it's more difficult and takes longer to learn for many students. This shape is also very dependent on an individual's shoulder flexibility, which could be restricted by body structure, former injuries, other training, etc. The straight handstand form is also more specific to modern day gymnastics and circus techniques, so depending on an individual's goals it may not be necessary to learn it strictly this way.
Though the straight handstand technique is desirable for many skills, it's still possible to achieve a very high level of ability without a straight handstand.

So, should you try to learn your handstand with this form? The general answer is yes. However, depending on your physiology, goals, and standards, it may not be your highest priority.